Both Democratic presidential candidates, Barack Obama and Hillary Clinton, are claiming Medicare could save over a trillion dollars if seniors could return to the obesity rates that existed in 1980.

Their numbers are off a little, though. They and other lawmakers probably got the idea that obesity costs big bucks from a RAND Corporation study by Eric Finkelstein. Obesity related diseases cost $200 billion, and cost Medicare and Medicaid an extra $39 billion, according to the RAND study.

Obese people, for example, are more likely to have diabetes, coronary disease and hypertension.

“If we rein in those profligate heavyweights, the thinking goes, we’ll save billions in taxpayer money,” said Daniel Engber in the Feb. 14 Slate.

For example, a Mississippi lawmaker proposed a bill making it illegal for restaurants to serve obese customers. After California Gov. Arnold Schwarzenegger claimed the state had $28.5 billion in obesity costs, politicians there tried to force restaurants to list calorie counts on their menus, Engber said.

“Politicians love to throw around cost-of-obesity numbers as support for fat-prevention programs, overeating legislation, or, in the case of Sens. Obama and Clinton, massive health-care reform,” Engber said.

New studies indicate trying to wring money out of the obese is misleading, however.

The first, a Dutch study in PLoS Medicine, found that obese people have shorter life spans. Elderly people are, by far, the costliest patients, so early deaths save taxpayers money, and slow down the Social Security and Medicaid crises.

Lifetime health expenditures were highest for healthy-living people of optimum weight, because they lived a long time, the Dutch study found.

A second study, in the American Journal of Public Health Jan. 30, found that body image had a much bigger impact on health than body size. Two women with similar insecurities would have similar health outcomes, even if one were fat and the other thin, Engber said.

The stigma associated with being obese is a major contributor to obesity-related disease and ill health. There is a strong association between body-mass index and depression, especially among women, according to the second study.

Engber proposed if the presidential candidates pledge support for a federal ban on weight-based discrimination, and stop blaming fat people for our problems, obese people will start feeling better and save us money.

It’s not likely to happen, however. Obese people, like smokers, make easy targets.